ACARINA — PARASITES. 



331 



to exist. Mites mjiltiply very rapidly ; they are hatched from eggs in 

 about eight days ; and if deprived of food, will kill and eat each other 

 very greedily. They infest almost the whole of our dried articles of 

 food. The parts of the mouth and legs of these acari can be best made 

 out by crushing the animal upon a glass slide, with a thin glass cover ; 

 then washing away the exuded substance with water — sometimes a hot 

 solution of potash is requisite, with the subsequent addition of acetic 

 acid and washing ; after drying, mount them in Canada balsam. 



The Aca/rus sacchari, or Sugar Insect. — There is very commonly 

 present in the more impure kinds of sugar a beetle-like animalcule of 

 the genus Aca/rus. The discovery of the very general presence of this 

 acarus rests, we believe, entirely with Dr. Hassall. 



The sugar acarus approaches somewhat, in organisation and habits, 

 the louse and the itch-insect ; it is in size so considerablCj that it is 

 plainly visible to the unaided sight. When present in sugar, it may 

 always be detected by the following proceeding : two or three drachms 

 or teaspoonfiUs of sugar should be dissolved in a large wine-glass of 

 tepid water, and the solution allowed to remain at rest for an hour or 

 so ; at the end of that time the animalcules will be found, some on the 

 surface of the liquid, some adhering to the sides of the glass, and 



fig. 158. 

 Ora and young of the Acarus sacchari, or Sugar-insect, after Hassall, 

 magnified 200 diameters. 



others at the bottom, mixed up with the copious and dark sediment, 

 formed of fragments of cane, woody fibre, grit, dirt, and starch granules, 

 which usually subsides on the solution of even a small quantity of sugar 



in water. 



We will now proceed to give a description of the acarus in question, 



